For sixteen years, from 1348 to 1364, Giovanni de̕ Dondi (1318-1389) conceived, designed, sketched and built his masterpiece in Padua: the Astrarium, as he himself called it, is a highly complex astronomical wheel clock. This mechanical clock has a weight drive and is the first spindle escapement in history.
The seven sides of the astrarium are formed by Equatoria (planetary calculators) for the sun, moon and the planets known at the time, Mercury, Venus, Mars, Jupiter and Saturn. The Earth is in the centre. De Dondi's astrarium was lost in 1630. Still, his detailed notes and sketches allowed for elaborate reconstructions, which can be seen in a few important museums today.
My friend and teacher, the Astrolabe maker Martin Brunold from Switzerland, made a scaled-down and simplified replica of the large model in 2007. The CHRONOS MANUFAKTUR will follow its construction plan.
Height approx. 300 mm (¼ of the original), brass. Depicted are the epicycles of the seven heavenly bodies as they run on the concentric deferent circle. Eccentricities and aequantum concepts according to Ptolemy not considered. Without clockwork. Driven by a hand crank on the lunar side. Planetary movements according to the principle of the original astrarium. One full rotation of the hand crank corresponds to one sidereal month and moves all planets on the seven sides of the astrarium, so that the retrograde motion of the planets in opposition can be observed.